MAIN DISTRIBUTION BOARDS
PART I -GENERAL
1.01 RELATED DOCUMENTS:
A. Drawings and general provisions of Contract, including General and
Supplementary Conditions and Division-1 Specification sections, apply to
work of this section.
B. Division-16 "Electrical Basic Materials and Methods" and other sections
apply to work -specified in this section.
1.02 SUMMARY:
A. This section includes Main Distribution Board (MDB) work as indicated by
drawings and schedules. (Main distribution boards fed from emergency
supply are prefixed with letter "E").
1. Relevance to codes or standards of this Specification.
2. Work includes mounting frames, fittings, cable termination accessories,
gland plates and supports.
B. Types of MDB's specified in t
his section are including the following:
1. Circuit-breaker MDB's, floor mounted with withdrawable or fixed circuit
breaker arrangements.
2. MDB's with incorporated automatic transfer switches as shown on
drawings.
C. Related Sections: the following sections of division 16 contain requirements
that relate to this Section:
"L V Circuit Breakers"
"Circuit and Motor Disconnects"
"L V Wires and Cables"
"Earthing".
"Identification".
"Transfer Switches".
-Refer also to division 15 section "Building Management System" for
connection to BMS.
- Connection to BMS system, including interface elements detailed in
BMS schedules and/or shown on the drawings.
1.03 SUBMITTALS:
A. Equipment Data: submit for approval detailed description of main
distribution boards and major components supported by manufacturers
catalogues, indicating compliance with the Standards, equipment
characteristics, details of construction, operating data, dimensions and
weights etc. Give details of miscellaneous items including incoming and
outgoing feeder terminal arrangement, connections at busbars, isolating,
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earthing, interlocks, control devices, indicating and metering instruments
etc.
B. Tests and Certificates: submit complete certified manufacturers type and
routine test records, in accordance with the Standards.
C. Shop and Construction Drawings: submit drawings for approval including,
but not limited to the following:
1- Plans and elevations with indication of built-on equipment, exact
dimensions and weights.
2- Arrangement of boards inside rooms allocated, indicating spaces and
clearances.
3- Arrangement of equipment inside board.
4- One-line diagram of power system showing current ratings of switch gear
and busbars and types and locations of protective gear (relays,
instruments, CTs, VTs etc.) .
5- Schematic and elementary diagrams of control circuits.
6- Foundation details, grouting holes, installation details.
7- Arrangement of incoming and outgoing feeders, terminal fittings,
instruments, busbar connections etc.
D. Technical Literature: submit the following for approval prior to placing
orders for equipment manufacture.
1- Schedule of circuit breaker application, indicating type, range, features
and characteristics, short- circuit ratings, time-current curves etc.
2- Method of setting of protective devices for overload, short-circuit and
earth-fault currents as coordinated with upstream and downstream
systems based on specific coordination curves of protective devices used
and specific calculated prospective short-circuit currents at various points
3- Test methods on site and references.
E. Selectivity Study
Submit to the Engineer a relay and C.B. selectivity study based on a fully
selective system.
The Current – time characteristics must be plotted on a log-log papers
showing that the choice of the C.B. settings are correct for full selective
system.
F. Short Circuit And Voltage Drop Calculation
Submit a comprehensive short circuit study as well as voltage drop
calculation based on the actual impedance values of the electrical components
such as supply short circuit level at the 11KV (shall not be less than 500
MVA), transformer per unit impedance, bus bars and cable
impedances….etc.
G. Load Balance
Submit a detailed load list verifying the load balance across the phases.
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1.04 SPARE PARTS AND TOOLS
A. Spare Parts: provide manufacturer's recommended spare parts for
emergency replacement and/or one year's maintenance including but not
limited to the following:
1. One set of fixed and moving contacts for every type of replaceable
contact set.
2. One operating motor and/or coil for each type of electrically operated
circuit breaker.
3. Two sets of each type and rating of indicating light, fuse, LED, control
switches, and similar devices subject to failure or breakage at any time.
B. Tools and Instruments: provide tools and instruments required for normal
routine inspection and maintenance and testing of circuit breakers and
protective devices as appropriate for type of switch gear supplied.
1.05 QUALITY ASSURANCE:
A. Manufacturer's Qualifications: firms regularly engaged in the manufacture
of main distribution boards, of types, sizes and capacities required, and
whose products have been in satisfactory use in similar service for not less
than 5 years.
B. Contractor's Qualifications: firm with at least 5 years of successful
installation experience on projects utilizing switchboard units similar to
those required for this project. .
C. Codes and Standards:
1. Standards
a. Switch gear and control gear are to comply as a minimum with IEC 439-1,
IEC 60974 Factory-Built Assemblies of Low Voltage Switch gear and
Control Gear.
b. Circuit breakers are to comply with IEC 947-2 and as specified in Section
"L V Circuit Breakers".
c. Other components, where not otherwise specified, are to comply with the
relevant IEC standards.
2. Electrical Regulations/Code Compliance: comply with applicable local
regulations/code requirements of the authority having jurisdiction. This
will have precedence over other codes/standards nominated for the
project, J unless otherwise approved in writing.
1.06 DELIVERY, STORAGE, AND HANDLING:
A. Deliver MDB's and components properly packaged and mounted on pallets,
or skids to facilitate handling of heavy items. Utilize factory-fabricated type
containers or wrappings for MDB's and components, which protect
equipment from damage. Install gravity measuring meters in containers
which indicates whether container has been bumped or dropped. Return
G-meters to manufacturer for reuse upon delivery of MDB's. Inspect
equipment to ensure that no damage has occurred during shipment
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B. Store MDBs in original packaging and protect from weather and
construction traffic. Wherever possible, store indoors; where necessary to
store outdoors, store above grade and enclose with watertight wrapping.
C. Handle MDBs carefully to prevent physical damage to equipment and
components. Remove packaging, including the opening of crates and
containers, avoiding the use of excessive hammering and jarring which
would damage the electrical equipment contained therein. Do not install
damaged equipment; remove from site and replace damaged equipment with
new.
1.07 SEQUENCING AND SCHEDULING:
A. Schedule delivery of MDB and accessories equipment which permits ready
building ingress for large equipment components to. their designated
installation spaces. Coordinate delivery of equipment with the Installation
of other building components.
B. Coordinate the size and location of concrete equipment pads. Cast anchor
bolt inserts into pad. Concrete, reinforcement, and formwork requirements
are, specified in Division 3.
C. Coordinate with. Other electrical work including raceways: electrical boxes
and fittings, and cabling/wiring work, as necessary to Interface Installation
of MDBs with other work.
PART 2 –PRODUCTS
2.01 MANUFACTURERS:
A. Available Manufacturers: subject to compliance with requirements,
specifications, drawings and regulations.
B. For approved manufacturers refer to the recommended manufacturer list.
2.02 GENERAL REQUIREMENTS:
A. Generally: main distribution boards are to be “BS standard” (Form 4) Metal
Clad multi-cubicle, floor mounted, free standing, 1000 V rated insulation
voltage and 600 V, rated operational voltage with fixed or draw-out switch
gear , manually or manually and electrically operated, as shown on the
Drawings, with matching vertical sections to form a continuous integral and
rigid structure, wired and type tested at the factory, ready for installation on
the site.
B. Connection to Building Management System: coordinate with the Building
Management System (BMS) supplier and provide all necessary interface
devices, dry contacts, relays, transducers, etc, for connection of the required
points to the BMS as specified or indicated in the BMS schedules.
C. General Construction: rigidly framed and bolted, with electro-galvanized
sheet steel enclosures, minimum thickness 2 mm, phosphatized, primed
with rust inhibiting primer and finished with thermal polymerized polyester
epoxy powder coating, grey colour (RAL 7703) to approval. Switchgear is
to be Vermin, dust and rodent proof, IP 42 protection to lEC 529 for indoor
installations, with adequate lifting means and base-frames and capable of
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being moved into position and directly bolted to floor without additional
sills.
D. Ventilation: compartments are to be Ventilated, where required, by
approved methods complying with the Standards.
E. All fastenings between structural members shall be bolted, not welded, to
provide flexibility during installation.
F. Extension of structure and busbars is to be possible end of switchboard.
G. Arrangement is to permit incoming. and outgoing busbars and cables to
enter enclosure as indicated on the Drawings and connect at respective
terminals without inconvenience to installation or maintenance.
H. Automatic transfer switches incorporated within switchboards are to be as.
shown on the drawings and to comply with section 16495.
I. Removing Circuit Breakers: suitable arrangements and equipment are to be
provided for extracting, lifting and unloading switchgear from enclosures
as appropriate for type of switchgear.
J. Spare and space positions are defined as follows:
spare position: fully equipped enclosure with switchgear
space position: fully equipped enclosure ready to receive switchgear.
K. Busbars: to be site rated for normal current as shown on the Drawings or at
least site rated to same rating as main circuit breaker size, and braced for a
symmetrical rms short- circuit duty equal to or higher than main circuit
breaker interrupting duty, for minimum of one second unless otherwise
specified or shown on the Drawings. Busbars are to be copper, of sufficient
size to limit temperature rise to allowable insulation or equipment
temperature ratings, and to a total maximum temperature of 90 deg. C.
Connections and buswork are to be bolted with copper alloy hardware and
are to be accessible for inspection and maintenance. Contact surfaces are to
be electro-silver plated.
L. Connections from busbar to switch gear are to be rated to carry full
continuous current rating of switch gear frame and are to be insulated.
M. Full size neutral is to be continuous through all sections. Neutral bus is to be
insulated and separate from earth bus and connected to it with removable
links.
N. Earth bus is to extend full length of board, firmly fixed to each section in
accordance with the Regulations and Standards, complete with two main
earthing lugs ( one at each end), and required number of feeder protective
earth connectors.
O. Switchboard Type: switchboard(s) are to be of the following type(s):
1. Form 4b to IEC 439-1 with metallic separation, is to be front and rear
accessible, front and rear aligned with withdrawable main and tie power
air circuit breaker (PACB)) sections (type and rating as shown in
Schedules) and fixed or withdrawab1e individually mounted outgoing P
ACB & MCCB distribution section(s). ( type and rating as shown in
schedules).
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P. Withdrawable metal enclosed circuit breaker section is to consist of
compartmented unit(s), stationary part with rear busbar and cable
connection compartments and front draw- out circuit breaker assembly.
Partitions between sections are to be bolted steel plate and partitions
between compartments are to be tough solid insulating removable bolted
barriers. Each unit is to have hinged lockable front door with grip-handle
and door mounted instrumentation.
Q. Drawout circuit breaker assembly is to have disconnecting contacts, wheels
and interlocks to prevent connecting or disconnecting circuit breaker unless
in the open position, and to prevent closing circuit breaker while racking
into any of the three positions ( connect, test, disconnect) .Racking
mechanism and rail assembly are to be approved worm and lever
mechanism. It is to be possible to close the unit door with breaker in any of
the three positions and when removed. External position indicator is to be
provided. Fixed disconnecting primary contacts are to be accessible and
replaceable from front and are to be silver plated copper. Moving primary
disconnect contacts are to consist of self- aligning, silver plated,. spring
pressure, finger-cluster copper contacts fitted on, line and load studs of
circuit breaker.
R. Front and rear accessories, front and rear aligned, individually mounted
fixed or withdrawable PACB or MCCB distribution sections as basic
construction for form 3 and form 4 switchboards, are to be
compartmentalized construction, consisting of front modular circuit breaker
compartments, busbar system compartments and rear sable termination
compartments ( as per the form type selected), with insulating barriers
between front compartments and busbar compartments and between rear
compartments and busbar compartments (removable for
maintenance).MCCBs are to be closely coupled to busbars (to minimize
chances of bus -side faults), and to rear cable terminals, through compatibly
frame -sized insulated connectors. MCCB modules are to be covered on the
front, by recessed frame -type bolted covers, 2 minimum thickness, to
protect circuit breaker handles. Top, sides and rear are to be covered with
removable screw-on plates having formed adages all around.
S. The Electrical installation has been designed to give load balance across the
phases as far as possible but it is the contractor's responsibility to maintain
or improve the balance when connections to bars etc.
T. When the final commissioning is to be completed the contractor shall allow
in his tender for checking loads and altering connections in order to achieve
as even a balance over the phases.
U. All busbar contact surfaces shall be electro-silver plated to a minimum
thickness of 0.0125 mm.
V. A special trolley shall be supplied together with the switchgear for removal
or installation of the air-circuit breakers from their compartment for
maintenance or repair.
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W. The switchgear shall be provided with inlet air filtration.
X. In case of MDB main incoming C.B tripping due to either under voltage or
over voltage the C.B shall come back automatically after voltage stability.
Y. All incoming circuit breakers shall be equipped with under and over voltage
shunt trip relays.
Z. It is not permitted for Bus coupler to switch over between transformers
automatically.
AA. No paralleling of transformers shall be allowed, interlocking system to
insure this function.
BB. Main incoming circuit breakers shall be able to be controlled via the B.M.S
system.
2.03 CIRCUIT BREAKERS:
A. Except as otherwise indicated, provide circuit breakers and ancillary
components, of types, sizes, ratings and electrical characteristics shown on
drawings, which comply with manufacturer's standard design, materials,
components, and construction -in accordance with published product
information, and as required for a complete installation and as approved by
the Engineer.
B. Provide circuit-breakers as specified in Division 16 Section "L V Circuit
Breakers", of the following types:
1. Power Air Circuit Breakers (PACB's); electrically and mechanically
operated, 3 or 4 pole as shown on the drawings.
2. Moulded Case Circuit Breakers (MCCB's) meeting with specification of
"MCCB's for MOB's:
C. Provide the following accessories as required on drawings:
1. Electrical operator.
2. Control and interlocking functions.
3. Undervoltage release.
4. shunt trip coil.
5 .alarm and auxil1ary switches.
6. padlocking device.
7. key lock device.
D. Non-fused current-limiting circuit breakers where high interrupting duty is
required for small normal current. ranges and with accessories as stated
above for MCCBs, as shown on drawings.
E. All components shall be installed in accordance with the instructions of
their manufacturers. This requirement does not negate the requirement for
type and routine testing as specified elsewhere in this specification.
F. Adjusting and resetting devices shall be easily accessible.
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G. All components shall be installed and wired such that their function is not
impaired by interaction such as heat, arcs, vibration, and fields or energy
present in normal operation.
H. Barriers for manual switching devices shall be designed such that arcs
caused by switching under normal operation or the interruption or making
of a fault current shall not present a danger to the operator.
I. All removable and withdrawable components shall be installed and
designed such that they can be safely disconnected or connected to supply
circuits while the associated conductors are live.
J. All spare contacts on relays, contactors, and the like shall be wired to easily
accessible terminal blocks, suitably positioned for future external wiring.
K. Assemblies shall be provided with a spare set of fuses mounted on
polyethylene coated spring clips adjacent to the fuse chart on the doors of a
separate cubicle. A total of 20% of each size of fuse shall be provided with a
minimum 4 of each size. When commissioning is complete the panel shall
be handed over with this complete set of spare fused. A fully detailed fuse
chart shall be provided in the same cubicle as the fuses.
L. Where moulded case circuit-breakers are installed they shall be fitted with
rotary action handles. The handles shall be lockable in the "ON" and "OFF"
positions.
2.04 METERING INSTRUMENTS
A. A microprocessor based monitoring device thal provide complete electrical
metering is to be provided for all the main incoming feeders.
B. The device is -provide reading of the items listed below with the following
accuracy:
current per phase : ± 0.5 %
Voltage per phase/line : ± 0.5 %
Power
Watts & Watts demand (min. & max.) : ± 1.0 %
Vars & Vars demand ( min. &max. ) : ± 1.0 %
V A & V A- demand (min. & max. ) : ±: 1.0 %
Power consumption:
Watt -Hours : ± 1.0 %
Var –Hours : ± 1.0 %
VA –Hours : ± 1.0 %
Power factor : ± 2.0 %
Frequency : ± 1.0 HZ
C. The device to be equipped with non- volatile storage of metered data at time
of last trip.
D. The device is to be provided with an addressable communication card
capable of transmitting, all data over a compatible two-wire local area
network to a central personal computer ( in the BMS room) for storage
and/or printout.
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E. The device is to be provided in a draw -out case, which shall permit rapid
interchanging of the device with similar unit withdraw requiring panel
wiring change. Current transformers secondary shall be automatically short
- circuiting contacts shall be visible from the front.
F. Current and voltage transformer required for the operation of the device are
to be provided.
G. Current transformer (CT): indoor dry type, rated secondary current 5 A.
Rated primary current, core size and accuracy are to be determined in
accordance with nominal current of plant protected, short -circuit level and
burden.
H. Voltage transformer (VT): to be provided where required, complete with
primary and secondary fuses and disconnecting device.
I. Cable terminations and space for terminations shall be suitable for the sizes
of cable called for in the design.
J. Terminal blocks shall be made of thermosetting melamine or polyamide
material with a low tracking index and good flame resistance, tested to
withstand a temperature rise of 90OC above ambient temperature. Provision
shall be made for permanent labels to be applied to each terminal for
identification purposes.
K. All terminals for control wiring shall have provision for plug-in test spills
and in addition be fitted with isolating links. Current carrying parts shall be
made of tinned brass or copper.
L. Completely shrouded terminals of the tunnel type shall be used for cables
up to 10mm2. The screw clamp connection shall be vibration proof,
self-locking and suitable for clamping two conductors.
2.05 BUS BARS
A. All copper bus bars, switching devices and connections shall be of
sufficient sizes and silver plated at contact to limit the temperature rise to
25OC over an average ambient temperature of 45OC outside the enclosure.
B. All bus bars and connections shall be accessible for inspection and
maintenance purposes.
C. Bus bars are to be of high conductivity copper and rigidly supported to
withstand the mechanical stress of a rated short-time withstand current in
accordance with IEC recommendation No. 60439-1.
D. Main bus shall be of continuous construction. Main bus joints and all top
connections shall be silver plated and tightly bolted to insure maximum
conductivity
E. Bus bars shall be clearly marked with their respective phase colors and
shall be furnished for future extensions.
F. The main set of bus bars shall be housed in segregated chamber. Bus bar
top covers shall be capable of supporting a main weight without
deflection.
G. Incoming and outgoing supplies to switchgears shall be either busways or
cables as indicated on drawings.
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H. A full length ground copper bus shall be provided. The ground bus shall
be founded to the metal enclosure of each compartment and to metering
and relaying, transformers secondary windings. Lugs shall be provided
one at each end of the ground bus and one in each cubicle for the user's
copper ground cables.
I. The cross sectional area of neutral bus bars shall not be less than of the
associated phase bars.
J. Access to bus bars and bus bar connections shall be possible only after the
removal of covers secured by bolts or studs. Such covers shall be
identified externally by engraved laminated labels bearing the inscription
" BUSBARS DANGER 380 VOLTS " in 30mm high black lettering on a
yellow background.
K. Connections from main and dropper busbars to the supply side of
functional units shall be by means of dedicated conductors. Conductors
installed on a loop in principle shall not be acceptable.
L. All neutral supply/load connections shall be made via the enclosure
containing the associated functional unit. Common neutral terminals shall
not be acceptable.
M. No diversity shall be used in busbar dropper sizing.
2.06 AUXILIARY WIRING
A. All non-screened auxiliary wiring, except that which is required to be
screened, shall be carried out on 600/1000V grade insulated, multistranded
flexible conductors.
B. The minimum conductor size shall be 1.5mm2
C. All auxiliary wiring shall be identified at both ends with numbered any
resistor color coded ferrules. These numbers shall be shown on the control
schematic wiring diagram.
D. All auxiliary wiring shall be contained within cabling trunking and totally
segregated from power wiring as far as practicable. Wiring of circuits at
different voltage categories, e.g L.V. and ELV, shall be segregated. Joints
will not be permitted on wiring between devices.
E. Cable trunking shall be of the ventilated type with clip-on covers and
purpose made junctions and accessories. Cable shall not occupy more than
40% of the trunking cross-sectional area.
F. Wiring not contained within trunking shall be strapped in looms with
removable straps and held in place by sutiable cleats. Looms shall not
exceed more than 25 wires. Self adhesive straps shall not be acceptable.
G. All wiring connections from trunking and looms to devices shall be run in
straight lines, horizontally and vertically, and be neatly dressed.
H. Wiring to door mounted devices shall be flexible and provided with a
large enough loop to clear the edge of the opening. Protection against
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abrasion shall be provided by means of flexible conduit or spiral wrapping
securely fixed at each end.
I. Where wiring passes through partitions it shall be protected against
abrasion by thermoplastic grommets and spiral wrapping.
J. Interconnections between functional units shall be contained within a
separate cabling chamber or trunking. All cables shall terminate on the
functional unit terminals within the cubicle.
2.07 LABELS
A. All enclosure containing functional units shall be clearly labeled with a
circuit, unit reference and current rating.
B. All labels shall be of the engraved type made from suitable multi-layer
laminate and shall be fixed with zinc plated cheese head instrument screws.
No other type of label will be acceptable.
C. Every functional unit shall be labeled separately from all others. External
labels shall have letters not less than 5mm in height and internal labels not
less than 3mm. the letters shall be black in color on a white background.
D. All covers/doors not fitted with interlocked switched disconnectors enclosing
unshrouded live equipment shall be fitted with warning labels inscribed
"DANGER 380V ISOLATE BEFORE OPENING".
E. Warning labels shall have black letters on a bright yellow background
wherever possible, letters shall be not less than 30mm in height. On small
covers and doors letters of 20mm or 10mm in height shall be used.
F. Cable boxed shall be clearly labeled both externally and internally with the
circuit and functional device number.
G. All terminal blocks shall be labeled relative to the respective functional unit.
H. Every control and metering device, selector switch, pushbutton and indicator
light shall be clearly labeled to indicate its purpose.
I. Main identification labels shall be provided on the assembly together with a
rating plate.
J. Fixed and withdrawable portions of equipment including fixed and plug-in
devices shall be labeled with withdrawable portions cross-referenced to their
fixed part.
K. Proposed engraving details shall be submitted for comment prior to engraving.
2.08 EARTHING
A. Each assembly shall be provided with a continuous copper earth bar running
the whole length sized for the prospective short-circuit current.
B. Discrete terminals shall be provided for connection to all the protective
conductors. Each individual section of the assembly shall be separately
bonded to the main earth bar.
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2.09 SELECTOR SWITCHES/PUSH-BUTTONS/INDICATOR LAMPS
A. The manufacturer's range shall include fully interchangeable contact blocks
and lamp holder blocks which can be fitted to all actuators including switches
and push-buttons.
B. Selector switches shall be of the rotary type, with lever or key operated
actuators.
C. Pushbuttons shall be of the flush type.
D. Pushbuttons used for emergency stop purposes shall be of the mushroom
head type, with a twist to release action or key reset.
E. Contact blocks shall have double break silver plated contacts, in "No" or
"NC" configuration rated at not less than 5A resistive at 220V 50 HZ.
F. Indicating lamps shall be of the flush type 22mm diameter with removable
colored lenses, allowing lamps to be changed from the front and shall be
provided with a push to test facility.
G. Indicating lamps on control circuits shall be equipped with completely sealed
dual wound safety isolating transformers and in-built test relay.
H. Fuse failure lamps shall be of the neon type with current limiting device.
2.10 POWER FACTOR (PF) CORRECTION
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A. Generally : multi-step PF correction system complete with multi-step
capacitor bank, regulator, anti-harmonic protective reactors and HRC fuses is
required to bring up power factor of LV system to better than 0.93. Each
transformers is to be provided with a separate multi-step power factor
correction system as shown on the Drawings.
B. Location of Capacitor Bank: is to be indoor type as close as possible to
nominated switchboard requiring PF improvement, and to be totally enclosed
in sheet metal cabinets with appropriate ventilation.
C. Capacitor Bank is to be prefabricated, complete with capacitors,
anti-harmonic reactors, contactors, busbars and power factor regulator, to
effect automatic control and sensing of power factor for switching in and out
the number of steps required to improve PF to at least the figure indicated
above, and discharge resistors to enable discharge of capacitors after
disconnection. The total rating and minimum number of steps of each
capacitor bank is indicated on the Drawings.
D. Steps are to be rated at maximum 50 KVA, 3-phase, operating for loads
between 100 KVA and 1800 KVA having PF below 0.93. Details and ratings
of capacitor steps and anti-harmonic reactors of each system are to be
calculated by the Contractor based on the final ratings and characteristics of
the selected equipment and taking into consideration the various operating
schemes. Calculations are to be submitted for approval.
E. Capacitors are to be dry-type, operating on rated low voltage, made of
metalized polypropylene (self-healing dielectric) foils coated with
thermosetting resin, or equal construction, proved in operation for at least 5
years, under prevailing ambient conditions. Capacitors are to comply with
IEC 381-1 & IEC 831-2, with a loss factor not exceeding 0.3x10(-3) (a
consumption of about 0.4 watts per KVAr). Capacitor with plastic
polypropylene dielectric, impregnated with vegetable non PCB impregnated
(fire point >= 300 deg C biodegradable, in aluminum casing is also
acceptable.
F. Switching of Capacitors is only to be performed by the fast closing contactors
on capacitor bank units (with surge limiting reactors as necessary). Switching
arrangement of capacitors is not to allow excessive transient capacitive
switching at source, i.e. circuit breaker feeding the bank.
G. Anti-harmonic reactors are to be connected in series with the capacitors and
properly tuned to limit the harmonic currents in order to avoid overloading
the capacitors. The reactor rating at 50 Hz is to be not less than 7% of power
capacity to be protected.
H. Accessories: each capacitor is to have its own connection terminals, HRC
fuses, contactor, indicator lamp and set of discharger resistors.
I. Regulator is to be housed IP31 sheet steel enclosure, and is to have setting
knob for PF selection between 0.8 and 1.0, manual control position, and
signal lights.
J. Instrument Transformers are to be provided at incoming circuit breaker(s) of
MDB.
2.11 WIRING
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A. Arrangement: wiring is to be modularly and neatly arranged on. master
terminal boards with suitable numbering strips and appropriate cartridge type
fuses where required.
B. Connections are to be made at front of terminal board and with no live metal
'exposed.
C. Metal cases of instruments, control switches, relays etc. are to be connected,
by copper conductors not less than 2.5 mm2 section, to nearest earthing bar.
D. Control Wiring: copper, PVC insulated, 85 deg. C, 600 V grade, and PVC
sheathed. for multi-core cables. Finely .stranded copper conductor, silicon
rubber insulated cables are to be used In proximity to higher temperature
components and as flexible cable.
E. Ferrules: wires are to be fitted with numbered ferrules of approved type at
each termination.
2.12 MISCELLANEOUS
A. Schematic and wiring diagram is to be provided suitably located within each
cubicle.
2.13 WORKS TESTS
A. All assemblies shall be tested in accordance with the requirements of IEC
60439 standards part 1, plus requirements of associated standards.
B. TYPE TESTED ASSEMBLIES (TTA)
TTAs are specified, certification shall be provided for all type and routine
tests to IEC 60439 standards.
C. TYPE TESTED ASSEMBLIES
TTAs are specified, compliance with the test requirements of IEC 60439.
Verification of the Type Testing Certification or the appropriate
extrapolation calculations shall be provided. Certificates shall also be
provided for routine tests.
D. Works tests shall include inspection of all wiring and a complete electrical
functioning test.
E. Protection relays shall be tested by primary current injection with currents
equal to overload, short-circuit and earth fault conditions.
F. Works tests shall be done in the presence of the engineer.
2.14 FIELD TESTING
A. ASSEMBLES
All assemblies shall be subjected to the routine tests as defined in IEC, 60439
standards. after installation on site. Test certificates shall be provided.
B. FUNCTIONAL UNITS
All functional units shall be checked for correct mechanical operation.
C. PROTECTION CIRCUITS
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All protection circuits in with relays used shall be tested for correct operation
by secondary injection of test currents. This shall be carried out at currents
equivalent to overload, short-circuit and earth fault conditions.
D. CURRENT TRANSFORMERS
Protection circuits using current transformer (CT) operated relays shall be
tested by primary injection of current to prove the transformer ratio.
2.15 COMMISSIONING
A. Following the satisfactory conclusion of inspections and tests on completed
sections of the works, each switchgear assembly shall be duly commissioned
and left in full working order. The term "Commissioning" shall be deemed to
include:
(1) The energizing of functional device circuits and equipment which have
previously been inspected, tested found to be satisfactory and capable of
being energized with compete safety.
(2) The starting up of all electrically powered plant and equipment, including
that supplied and installed under other contracts, and as specified in the
schedules.
(3) The verification of the performance of each switchgear assembly relative to
all such plant and equipment by the carrying out where required, of further
tests and the making of all necessary adjustments or as to obtain optimum
performance.
(4) The proving of all interlock operations in all possible combinations and the
operation of all control systems, metering and indications to meet the
performance requirements specified.
16
PART 3- EXECUTION
3.01 EXAMINATION:
A. Examine areas and conditions under which switchboards and components are
to be installed, and notify Engineer in writing of conditions detrimental to
proper completion of the work. Do not proceed with the work until
unsatisfactory conditions have been corrected in a manner acceptable to the
Installer.
3.02 INSTALLATION OF SWITCHBOARDS.
A. Install switchboards as indicated, in accordance with manufacturer's written
instructions, and with recognized industry practices; complying with
applicable requirements of applicable standards or codes approved.
B. Equipment Bases: ensure that concrete bases and foundations provided for
installation of equipment are constructed in accordance with approved shop
and construction drawings and equipment manufacturers' drawings and that
holes for fixing bolts and provisions for passage of cables etc. are provided as
required.
C. Built-in items: ensure that equipment supports, fixings and the like, and
sleeves for passage of feeders and cables which are to be built into concrete
foundations, bases, cable trenches or building structure are provided as and
when required and that they are properly installed.
D. Equipment: install on concrete bases etc., and assemble completely plumb
and level, before grouting in holding-down bolts.
E. Supports and Terminations: install all incoming and outgoing cable supports,
cable ends and termination fittings required for power and control cables.
F. Relays: set in accordance with manufacturer's instructions and in accordance
with an approved scheme.
G. Make good damaged painted surfaces, clean and apply rust-inhibiting prime
coat and two finishing coats of approved enamel upon delivery of equipment
to site, or as required by the Engineer.
H. Tighten connectors and terminals, including screws and bolts, in accordance
with equipment manufacturer's published torque tightening values for
equipment connectors. Where manufacturer's torque requirements are not
indicated, tighten connectors and terminals to comply with tightening torques
specified in applicable standards.
I. Coordinate as necessary to interface installation of switchgears with other
works.
J. Fasten enclosures firmly to wall and structural surfaces, ensuring that they are
permanently and mechanically anchored. Provide all angle units and
accessories for proper mounting.
K. Provide properly wired electrical connections for switchgears within
enclosures.
17
L. Double lugging is not permitted.
M. Fill out switchgears circuit directory card upon completion of installation
work.
N. Provide equipment earthing connections sufficiently tight to assure a
permanent and effective ground for panelboards.
O. Provide 6.0 mm minimum thick x100 cm wide insulation mat in front of low
voltage switchgear and near of freestanding equipment and extend 50cm
beyond ends.
3.03 FIELD QUALITY CONTROL:
A. Equipment: inspect equipment upon delivery to Site and report any damage
to the Engineer.
B. Switch gear: inspect and check switch gear for completeness, component
ratings, types, sizes, and wiring connections. Check phasing of busbars,
contacts and clearances.
C. Tests: after installation and before handover, carry out all tests required by
the governing codes and any other tests the Engineer may require to check
compliance of installation with the Specification, including insulation
resistance tests and operational tests.
D. Main and Control Circuits: using 1000 V megger (2000 Megohm range),
check insulation resistance between phases, between phases and
earth/enclosure and between neutral and earth.
E. Primary Injection Tests: provide portable test equipment to test time-delay
characteristics of circuit breakers by simulating an overload or fault
condition. Measure and record all test results and ambient conditions and
compare with manufacturer's data.
F. Instantaneous Trip Elements: test by high current primary injection, using
high- current primary injection test- sets and report all readings.
G. Routine tests on site are to be carried out on every main distribution board in
accordance with the Standard specified (IEC 439 or BS 5486: Part 1) for
FBAs assembled from standardized components outside the works of the
manufacturer. Routine tests are also to be carried out on every FBA,
delivered to site, if requested by the Engineer.
H. Prior to energization of circuitry, check all accessible connections to
manufacturer's torque tightening specifications.
I. Prior to energization of switchboards, check with ground resistance tester
phase-to-phase and phase-to-ground insulation resistance levels to ensure
requirements are fulfilled.
J. Prior to energization, check switchboards for electrical continuity of circuits,
and for short-circuits.
K. Equipment shall be tested and full type test certificate issued by an approved
independent test laboratory shall be submitted.
L. Adjust operating mechanisms for free mechanical movement.
18
M. After energization check phase balancing and adjust accordingly.
N. Touch-up scratched or marred surfaces to match original finishes.
3.04 ADJUSTING AND CLEANING:
A. Adjust operating mechanisms for free mechanical movement.
B. Touch-up scratched or marred surfaces to match original finishes.
3.05 EARTHING:
A. Provide equipment earthing connections for switchboards as indicated.
Tighten 1 connections to comply with tightening torques specified in
applicable standards to assure permanent and effective earthing.
3.06 DEMONSTRATION:
A. Subsequent to wire and cable hook-ups, energize switchboards and
demonstrate functioning in accordance with requirements. Where necessary,
correct malfunctioning units, and then retest to demonstrate compliance.
3.07 INTER CONNECTION WITH OTHER SYSTEMS
A. The system supplier is responsible to provide all required switches, auxiliary
contacts relays, wiring terminal blocks transducers to provide signaling and
metering information for the building management system (BMS) to accept
START/STOP, open/close, set point from it.
B. Relevant signals are listed under controls, (BMS) and motor control panels
drawings and data schedules.
C. All signals to BMS system should be potential free to actuate devices of less
than 20 VA.@220 volt.
D. If any device will need more than 20 VA. at any operating condition the
supplier should add interposing relays.
E. All analog measures coming or going to the (BMS) should be coordinate
with the (BMS) supplier (either 4-20 MA or 1-5 volt or -10 volt) or directly
connected to the (BMS) communication bus.
END OF SECTION 16425
PART I -GENERAL
1.01 RELATED DOCUMENTS:
A. Drawings and general provisions of Contract, including General and
Supplementary Conditions and Division-1 Specification sections, apply to
work of this section.
B. Division-16 "Electrical Basic Materials and Methods" and other sections
apply to work -specified in this section.
1.02 SUMMARY:
A. This section includes Main Distribution Board (MDB) work as indicated by
drawings and schedules. (Main distribution boards fed from emergency
supply are prefixed with letter "E").
1. Relevance to codes or standards of this Specification.
2. Work includes mounting frames, fittings, cable termination accessories,
gland plates and supports.
B. Types of MDB's specified in t
his section are including the following:
1. Circuit-breaker MDB's, floor mounted with withdrawable or fixed circuit
breaker arrangements.
2. MDB's with incorporated automatic transfer switches as shown on
drawings.
C. Related Sections: the following sections of division 16 contain requirements
that relate to this Section:
"L V Circuit Breakers"
"Circuit and Motor Disconnects"
"L V Wires and Cables"
"Earthing".
"Identification".
"Transfer Switches".
-Refer also to division 15 section "Building Management System" for
connection to BMS.
- Connection to BMS system, including interface elements detailed in
BMS schedules and/or shown on the drawings.
1.03 SUBMITTALS:
A. Equipment Data: submit for approval detailed description of main
distribution boards and major components supported by manufacturers
catalogues, indicating compliance with the Standards, equipment
characteristics, details of construction, operating data, dimensions and
weights etc. Give details of miscellaneous items including incoming and
outgoing feeder terminal arrangement, connections at busbars, isolating,
2
earthing, interlocks, control devices, indicating and metering instruments
etc.
B. Tests and Certificates: submit complete certified manufacturers type and
routine test records, in accordance with the Standards.
C. Shop and Construction Drawings: submit drawings for approval including,
but not limited to the following:
1- Plans and elevations with indication of built-on equipment, exact
dimensions and weights.
2- Arrangement of boards inside rooms allocated, indicating spaces and
clearances.
3- Arrangement of equipment inside board.
4- One-line diagram of power system showing current ratings of switch gear
and busbars and types and locations of protective gear (relays,
instruments, CTs, VTs etc.) .
5- Schematic and elementary diagrams of control circuits.
6- Foundation details, grouting holes, installation details.
7- Arrangement of incoming and outgoing feeders, terminal fittings,
instruments, busbar connections etc.
D. Technical Literature: submit the following for approval prior to placing
orders for equipment manufacture.
1- Schedule of circuit breaker application, indicating type, range, features
and characteristics, short- circuit ratings, time-current curves etc.
2- Method of setting of protective devices for overload, short-circuit and
earth-fault currents as coordinated with upstream and downstream
systems based on specific coordination curves of protective devices used
and specific calculated prospective short-circuit currents at various points
3- Test methods on site and references.
E. Selectivity Study
Submit to the Engineer a relay and C.B. selectivity study based on a fully
selective system.
The Current – time characteristics must be plotted on a log-log papers
showing that the choice of the C.B. settings are correct for full selective
system.
F. Short Circuit And Voltage Drop Calculation
Submit a comprehensive short circuit study as well as voltage drop
calculation based on the actual impedance values of the electrical components
such as supply short circuit level at the 11KV (shall not be less than 500
MVA), transformer per unit impedance, bus bars and cable
impedances….etc.
G. Load Balance
Submit a detailed load list verifying the load balance across the phases.
3
1.04 SPARE PARTS AND TOOLS
A. Spare Parts: provide manufacturer's recommended spare parts for
emergency replacement and/or one year's maintenance including but not
limited to the following:
1. One set of fixed and moving contacts for every type of replaceable
contact set.
2. One operating motor and/or coil for each type of electrically operated
circuit breaker.
3. Two sets of each type and rating of indicating light, fuse, LED, control
switches, and similar devices subject to failure or breakage at any time.
B. Tools and Instruments: provide tools and instruments required for normal
routine inspection and maintenance and testing of circuit breakers and
protective devices as appropriate for type of switch gear supplied.
1.05 QUALITY ASSURANCE:
A. Manufacturer's Qualifications: firms regularly engaged in the manufacture
of main distribution boards, of types, sizes and capacities required, and
whose products have been in satisfactory use in similar service for not less
than 5 years.
B. Contractor's Qualifications: firm with at least 5 years of successful
installation experience on projects utilizing switchboard units similar to
those required for this project. .
C. Codes and Standards:
1. Standards
a. Switch gear and control gear are to comply as a minimum with IEC 439-1,
IEC 60974 Factory-Built Assemblies of Low Voltage Switch gear and
Control Gear.
b. Circuit breakers are to comply with IEC 947-2 and as specified in Section
"L V Circuit Breakers".
c. Other components, where not otherwise specified, are to comply with the
relevant IEC standards.
2. Electrical Regulations/Code Compliance: comply with applicable local
regulations/code requirements of the authority having jurisdiction. This
will have precedence over other codes/standards nominated for the
project, J unless otherwise approved in writing.
1.06 DELIVERY, STORAGE, AND HANDLING:
A. Deliver MDB's and components properly packaged and mounted on pallets,
or skids to facilitate handling of heavy items. Utilize factory-fabricated type
containers or wrappings for MDB's and components, which protect
equipment from damage. Install gravity measuring meters in containers
which indicates whether container has been bumped or dropped. Return
G-meters to manufacturer for reuse upon delivery of MDB's. Inspect
equipment to ensure that no damage has occurred during shipment
4
B. Store MDBs in original packaging and protect from weather and
construction traffic. Wherever possible, store indoors; where necessary to
store outdoors, store above grade and enclose with watertight wrapping.
C. Handle MDBs carefully to prevent physical damage to equipment and
components. Remove packaging, including the opening of crates and
containers, avoiding the use of excessive hammering and jarring which
would damage the electrical equipment contained therein. Do not install
damaged equipment; remove from site and replace damaged equipment with
new.
1.07 SEQUENCING AND SCHEDULING:
A. Schedule delivery of MDB and accessories equipment which permits ready
building ingress for large equipment components to. their designated
installation spaces. Coordinate delivery of equipment with the Installation
of other building components.
B. Coordinate the size and location of concrete equipment pads. Cast anchor
bolt inserts into pad. Concrete, reinforcement, and formwork requirements
are, specified in Division 3.
C. Coordinate with. Other electrical work including raceways: electrical boxes
and fittings, and cabling/wiring work, as necessary to Interface Installation
of MDBs with other work.
PART 2 –PRODUCTS
2.01 MANUFACTURERS:
A. Available Manufacturers: subject to compliance with requirements,
specifications, drawings and regulations.
B. For approved manufacturers refer to the recommended manufacturer list.
2.02 GENERAL REQUIREMENTS:
A. Generally: main distribution boards are to be “BS standard” (Form 4) Metal
Clad multi-cubicle, floor mounted, free standing, 1000 V rated insulation
voltage and 600 V, rated operational voltage with fixed or draw-out switch
gear , manually or manually and electrically operated, as shown on the
Drawings, with matching vertical sections to form a continuous integral and
rigid structure, wired and type tested at the factory, ready for installation on
the site.
B. Connection to Building Management System: coordinate with the Building
Management System (BMS) supplier and provide all necessary interface
devices, dry contacts, relays, transducers, etc, for connection of the required
points to the BMS as specified or indicated in the BMS schedules.
C. General Construction: rigidly framed and bolted, with electro-galvanized
sheet steel enclosures, minimum thickness 2 mm, phosphatized, primed
with rust inhibiting primer and finished with thermal polymerized polyester
epoxy powder coating, grey colour (RAL 7703) to approval. Switchgear is
to be Vermin, dust and rodent proof, IP 42 protection to lEC 529 for indoor
installations, with adequate lifting means and base-frames and capable of
5
being moved into position and directly bolted to floor without additional
sills.
D. Ventilation: compartments are to be Ventilated, where required, by
approved methods complying with the Standards.
E. All fastenings between structural members shall be bolted, not welded, to
provide flexibility during installation.
F. Extension of structure and busbars is to be possible end of switchboard.
G. Arrangement is to permit incoming. and outgoing busbars and cables to
enter enclosure as indicated on the Drawings and connect at respective
terminals without inconvenience to installation or maintenance.
H. Automatic transfer switches incorporated within switchboards are to be as.
shown on the drawings and to comply with section 16495.
I. Removing Circuit Breakers: suitable arrangements and equipment are to be
provided for extracting, lifting and unloading switchgear from enclosures
as appropriate for type of switchgear.
J. Spare and space positions are defined as follows:
spare position: fully equipped enclosure with switchgear
space position: fully equipped enclosure ready to receive switchgear.
K. Busbars: to be site rated for normal current as shown on the Drawings or at
least site rated to same rating as main circuit breaker size, and braced for a
symmetrical rms short- circuit duty equal to or higher than main circuit
breaker interrupting duty, for minimum of one second unless otherwise
specified or shown on the Drawings. Busbars are to be copper, of sufficient
size to limit temperature rise to allowable insulation or equipment
temperature ratings, and to a total maximum temperature of 90 deg. C.
Connections and buswork are to be bolted with copper alloy hardware and
are to be accessible for inspection and maintenance. Contact surfaces are to
be electro-silver plated.
L. Connections from busbar to switch gear are to be rated to carry full
continuous current rating of switch gear frame and are to be insulated.
M. Full size neutral is to be continuous through all sections. Neutral bus is to be
insulated and separate from earth bus and connected to it with removable
links.
N. Earth bus is to extend full length of board, firmly fixed to each section in
accordance with the Regulations and Standards, complete with two main
earthing lugs ( one at each end), and required number of feeder protective
earth connectors.
O. Switchboard Type: switchboard(s) are to be of the following type(s):
1. Form 4b to IEC 439-1 with metallic separation, is to be front and rear
accessible, front and rear aligned with withdrawable main and tie power
air circuit breaker (PACB)) sections (type and rating as shown in
Schedules) and fixed or withdrawab1e individually mounted outgoing P
ACB & MCCB distribution section(s). ( type and rating as shown in
schedules).
6
P. Withdrawable metal enclosed circuit breaker section is to consist of
compartmented unit(s), stationary part with rear busbar and cable
connection compartments and front draw- out circuit breaker assembly.
Partitions between sections are to be bolted steel plate and partitions
between compartments are to be tough solid insulating removable bolted
barriers. Each unit is to have hinged lockable front door with grip-handle
and door mounted instrumentation.
Q. Drawout circuit breaker assembly is to have disconnecting contacts, wheels
and interlocks to prevent connecting or disconnecting circuit breaker unless
in the open position, and to prevent closing circuit breaker while racking
into any of the three positions ( connect, test, disconnect) .Racking
mechanism and rail assembly are to be approved worm and lever
mechanism. It is to be possible to close the unit door with breaker in any of
the three positions and when removed. External position indicator is to be
provided. Fixed disconnecting primary contacts are to be accessible and
replaceable from front and are to be silver plated copper. Moving primary
disconnect contacts are to consist of self- aligning, silver plated,. spring
pressure, finger-cluster copper contacts fitted on, line and load studs of
circuit breaker.
R. Front and rear accessories, front and rear aligned, individually mounted
fixed or withdrawable PACB or MCCB distribution sections as basic
construction for form 3 and form 4 switchboards, are to be
compartmentalized construction, consisting of front modular circuit breaker
compartments, busbar system compartments and rear sable termination
compartments ( as per the form type selected), with insulating barriers
between front compartments and busbar compartments and between rear
compartments and busbar compartments (removable for
maintenance).MCCBs are to be closely coupled to busbars (to minimize
chances of bus -side faults), and to rear cable terminals, through compatibly
frame -sized insulated connectors. MCCB modules are to be covered on the
front, by recessed frame -type bolted covers, 2 minimum thickness, to
protect circuit breaker handles. Top, sides and rear are to be covered with
removable screw-on plates having formed adages all around.
S. The Electrical installation has been designed to give load balance across the
phases as far as possible but it is the contractor's responsibility to maintain
or improve the balance when connections to bars etc.
T. When the final commissioning is to be completed the contractor shall allow
in his tender for checking loads and altering connections in order to achieve
as even a balance over the phases.
U. All busbar contact surfaces shall be electro-silver plated to a minimum
thickness of 0.0125 mm.
V. A special trolley shall be supplied together with the switchgear for removal
or installation of the air-circuit breakers from their compartment for
maintenance or repair.
7
W. The switchgear shall be provided with inlet air filtration.
X. In case of MDB main incoming C.B tripping due to either under voltage or
over voltage the C.B shall come back automatically after voltage stability.
Y. All incoming circuit breakers shall be equipped with under and over voltage
shunt trip relays.
Z. It is not permitted for Bus coupler to switch over between transformers
automatically.
AA. No paralleling of transformers shall be allowed, interlocking system to
insure this function.
BB. Main incoming circuit breakers shall be able to be controlled via the B.M.S
system.
2.03 CIRCUIT BREAKERS:
A. Except as otherwise indicated, provide circuit breakers and ancillary
components, of types, sizes, ratings and electrical characteristics shown on
drawings, which comply with manufacturer's standard design, materials,
components, and construction -in accordance with published product
information, and as required for a complete installation and as approved by
the Engineer.
B. Provide circuit-breakers as specified in Division 16 Section "L V Circuit
Breakers", of the following types:
1. Power Air Circuit Breakers (PACB's); electrically and mechanically
operated, 3 or 4 pole as shown on the drawings.
2. Moulded Case Circuit Breakers (MCCB's) meeting with specification of
"MCCB's for MOB's:
C. Provide the following accessories as required on drawings:
1. Electrical operator.
2. Control and interlocking functions.
3. Undervoltage release.
4. shunt trip coil.
5 .alarm and auxil1ary switches.
6. padlocking device.
7. key lock device.
D. Non-fused current-limiting circuit breakers where high interrupting duty is
required for small normal current. ranges and with accessories as stated
above for MCCBs, as shown on drawings.
E. All components shall be installed in accordance with the instructions of
their manufacturers. This requirement does not negate the requirement for
type and routine testing as specified elsewhere in this specification.
F. Adjusting and resetting devices shall be easily accessible.
8
G. All components shall be installed and wired such that their function is not
impaired by interaction such as heat, arcs, vibration, and fields or energy
present in normal operation.
H. Barriers for manual switching devices shall be designed such that arcs
caused by switching under normal operation or the interruption or making
of a fault current shall not present a danger to the operator.
I. All removable and withdrawable components shall be installed and
designed such that they can be safely disconnected or connected to supply
circuits while the associated conductors are live.
J. All spare contacts on relays, contactors, and the like shall be wired to easily
accessible terminal blocks, suitably positioned for future external wiring.
K. Assemblies shall be provided with a spare set of fuses mounted on
polyethylene coated spring clips adjacent to the fuse chart on the doors of a
separate cubicle. A total of 20% of each size of fuse shall be provided with a
minimum 4 of each size. When commissioning is complete the panel shall
be handed over with this complete set of spare fused. A fully detailed fuse
chart shall be provided in the same cubicle as the fuses.
L. Where moulded case circuit-breakers are installed they shall be fitted with
rotary action handles. The handles shall be lockable in the "ON" and "OFF"
positions.
2.04 METERING INSTRUMENTS
A. A microprocessor based monitoring device thal provide complete electrical
metering is to be provided for all the main incoming feeders.
B. The device is -provide reading of the items listed below with the following
accuracy:
current per phase : ± 0.5 %
Voltage per phase/line : ± 0.5 %
Power
Watts & Watts demand (min. & max.) : ± 1.0 %
Vars & Vars demand ( min. &max. ) : ± 1.0 %
V A & V A- demand (min. & max. ) : ±: 1.0 %
Power consumption:
Watt -Hours : ± 1.0 %
Var –Hours : ± 1.0 %
VA –Hours : ± 1.0 %
Power factor : ± 2.0 %
Frequency : ± 1.0 HZ
C. The device to be equipped with non- volatile storage of metered data at time
of last trip.
D. The device is to be provided with an addressable communication card
capable of transmitting, all data over a compatible two-wire local area
network to a central personal computer ( in the BMS room) for storage
and/or printout.
9
E. The device is to be provided in a draw -out case, which shall permit rapid
interchanging of the device with similar unit withdraw requiring panel
wiring change. Current transformers secondary shall be automatically short
- circuiting contacts shall be visible from the front.
F. Current and voltage transformer required for the operation of the device are
to be provided.
G. Current transformer (CT): indoor dry type, rated secondary current 5 A.
Rated primary current, core size and accuracy are to be determined in
accordance with nominal current of plant protected, short -circuit level and
burden.
H. Voltage transformer (VT): to be provided where required, complete with
primary and secondary fuses and disconnecting device.
I. Cable terminations and space for terminations shall be suitable for the sizes
of cable called for in the design.
J. Terminal blocks shall be made of thermosetting melamine or polyamide
material with a low tracking index and good flame resistance, tested to
withstand a temperature rise of 90OC above ambient temperature. Provision
shall be made for permanent labels to be applied to each terminal for
identification purposes.
K. All terminals for control wiring shall have provision for plug-in test spills
and in addition be fitted with isolating links. Current carrying parts shall be
made of tinned brass or copper.
L. Completely shrouded terminals of the tunnel type shall be used for cables
up to 10mm2. The screw clamp connection shall be vibration proof,
self-locking and suitable for clamping two conductors.
2.05 BUS BARS
A. All copper bus bars, switching devices and connections shall be of
sufficient sizes and silver plated at contact to limit the temperature rise to
25OC over an average ambient temperature of 45OC outside the enclosure.
B. All bus bars and connections shall be accessible for inspection and
maintenance purposes.
C. Bus bars are to be of high conductivity copper and rigidly supported to
withstand the mechanical stress of a rated short-time withstand current in
accordance with IEC recommendation No. 60439-1.
D. Main bus shall be of continuous construction. Main bus joints and all top
connections shall be silver plated and tightly bolted to insure maximum
conductivity
E. Bus bars shall be clearly marked with their respective phase colors and
shall be furnished for future extensions.
F. The main set of bus bars shall be housed in segregated chamber. Bus bar
top covers shall be capable of supporting a main weight without
deflection.
G. Incoming and outgoing supplies to switchgears shall be either busways or
cables as indicated on drawings.
10
H. A full length ground copper bus shall be provided. The ground bus shall
be founded to the metal enclosure of each compartment and to metering
and relaying, transformers secondary windings. Lugs shall be provided
one at each end of the ground bus and one in each cubicle for the user's
copper ground cables.
I. The cross sectional area of neutral bus bars shall not be less than of the
associated phase bars.
J. Access to bus bars and bus bar connections shall be possible only after the
removal of covers secured by bolts or studs. Such covers shall be
identified externally by engraved laminated labels bearing the inscription
" BUSBARS DANGER 380 VOLTS " in 30mm high black lettering on a
yellow background.
K. Connections from main and dropper busbars to the supply side of
functional units shall be by means of dedicated conductors. Conductors
installed on a loop in principle shall not be acceptable.
L. All neutral supply/load connections shall be made via the enclosure
containing the associated functional unit. Common neutral terminals shall
not be acceptable.
M. No diversity shall be used in busbar dropper sizing.
2.06 AUXILIARY WIRING
A. All non-screened auxiliary wiring, except that which is required to be
screened, shall be carried out on 600/1000V grade insulated, multistranded
flexible conductors.
B. The minimum conductor size shall be 1.5mm2
C. All auxiliary wiring shall be identified at both ends with numbered any
resistor color coded ferrules. These numbers shall be shown on the control
schematic wiring diagram.
D. All auxiliary wiring shall be contained within cabling trunking and totally
segregated from power wiring as far as practicable. Wiring of circuits at
different voltage categories, e.g L.V. and ELV, shall be segregated. Joints
will not be permitted on wiring between devices.
E. Cable trunking shall be of the ventilated type with clip-on covers and
purpose made junctions and accessories. Cable shall not occupy more than
40% of the trunking cross-sectional area.
F. Wiring not contained within trunking shall be strapped in looms with
removable straps and held in place by sutiable cleats. Looms shall not
exceed more than 25 wires. Self adhesive straps shall not be acceptable.
G. All wiring connections from trunking and looms to devices shall be run in
straight lines, horizontally and vertically, and be neatly dressed.
H. Wiring to door mounted devices shall be flexible and provided with a
large enough loop to clear the edge of the opening. Protection against
11
abrasion shall be provided by means of flexible conduit or spiral wrapping
securely fixed at each end.
I. Where wiring passes through partitions it shall be protected against
abrasion by thermoplastic grommets and spiral wrapping.
J. Interconnections between functional units shall be contained within a
separate cabling chamber or trunking. All cables shall terminate on the
functional unit terminals within the cubicle.
2.07 LABELS
A. All enclosure containing functional units shall be clearly labeled with a
circuit, unit reference and current rating.
B. All labels shall be of the engraved type made from suitable multi-layer
laminate and shall be fixed with zinc plated cheese head instrument screws.
No other type of label will be acceptable.
C. Every functional unit shall be labeled separately from all others. External
labels shall have letters not less than 5mm in height and internal labels not
less than 3mm. the letters shall be black in color on a white background.
D. All covers/doors not fitted with interlocked switched disconnectors enclosing
unshrouded live equipment shall be fitted with warning labels inscribed
"DANGER 380V ISOLATE BEFORE OPENING".
E. Warning labels shall have black letters on a bright yellow background
wherever possible, letters shall be not less than 30mm in height. On small
covers and doors letters of 20mm or 10mm in height shall be used.
F. Cable boxed shall be clearly labeled both externally and internally with the
circuit and functional device number.
G. All terminal blocks shall be labeled relative to the respective functional unit.
H. Every control and metering device, selector switch, pushbutton and indicator
light shall be clearly labeled to indicate its purpose.
I. Main identification labels shall be provided on the assembly together with a
rating plate.
J. Fixed and withdrawable portions of equipment including fixed and plug-in
devices shall be labeled with withdrawable portions cross-referenced to their
fixed part.
K. Proposed engraving details shall be submitted for comment prior to engraving.
2.08 EARTHING
A. Each assembly shall be provided with a continuous copper earth bar running
the whole length sized for the prospective short-circuit current.
B. Discrete terminals shall be provided for connection to all the protective
conductors. Each individual section of the assembly shall be separately
bonded to the main earth bar.
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2.09 SELECTOR SWITCHES/PUSH-BUTTONS/INDICATOR LAMPS
A. The manufacturer's range shall include fully interchangeable contact blocks
and lamp holder blocks which can be fitted to all actuators including switches
and push-buttons.
B. Selector switches shall be of the rotary type, with lever or key operated
actuators.
C. Pushbuttons shall be of the flush type.
D. Pushbuttons used for emergency stop purposes shall be of the mushroom
head type, with a twist to release action or key reset.
E. Contact blocks shall have double break silver plated contacts, in "No" or
"NC" configuration rated at not less than 5A resistive at 220V 50 HZ.
F. Indicating lamps shall be of the flush type 22mm diameter with removable
colored lenses, allowing lamps to be changed from the front and shall be
provided with a push to test facility.
G. Indicating lamps on control circuits shall be equipped with completely sealed
dual wound safety isolating transformers and in-built test relay.
H. Fuse failure lamps shall be of the neon type with current limiting device.
2.10 POWER FACTOR (PF) CORRECTION
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A. Generally : multi-step PF correction system complete with multi-step
capacitor bank, regulator, anti-harmonic protective reactors and HRC fuses is
required to bring up power factor of LV system to better than 0.93. Each
transformers is to be provided with a separate multi-step power factor
correction system as shown on the Drawings.
B. Location of Capacitor Bank: is to be indoor type as close as possible to
nominated switchboard requiring PF improvement, and to be totally enclosed
in sheet metal cabinets with appropriate ventilation.
C. Capacitor Bank is to be prefabricated, complete with capacitors,
anti-harmonic reactors, contactors, busbars and power factor regulator, to
effect automatic control and sensing of power factor for switching in and out
the number of steps required to improve PF to at least the figure indicated
above, and discharge resistors to enable discharge of capacitors after
disconnection. The total rating and minimum number of steps of each
capacitor bank is indicated on the Drawings.
D. Steps are to be rated at maximum 50 KVA, 3-phase, operating for loads
between 100 KVA and 1800 KVA having PF below 0.93. Details and ratings
of capacitor steps and anti-harmonic reactors of each system are to be
calculated by the Contractor based on the final ratings and characteristics of
the selected equipment and taking into consideration the various operating
schemes. Calculations are to be submitted for approval.
E. Capacitors are to be dry-type, operating on rated low voltage, made of
metalized polypropylene (self-healing dielectric) foils coated with
thermosetting resin, or equal construction, proved in operation for at least 5
years, under prevailing ambient conditions. Capacitors are to comply with
IEC 381-1 & IEC 831-2, with a loss factor not exceeding 0.3x10(-3) (a
consumption of about 0.4 watts per KVAr). Capacitor with plastic
polypropylene dielectric, impregnated with vegetable non PCB impregnated
(fire point >= 300 deg C biodegradable, in aluminum casing is also
acceptable.
F. Switching of Capacitors is only to be performed by the fast closing contactors
on capacitor bank units (with surge limiting reactors as necessary). Switching
arrangement of capacitors is not to allow excessive transient capacitive
switching at source, i.e. circuit breaker feeding the bank.
G. Anti-harmonic reactors are to be connected in series with the capacitors and
properly tuned to limit the harmonic currents in order to avoid overloading
the capacitors. The reactor rating at 50 Hz is to be not less than 7% of power
capacity to be protected.
H. Accessories: each capacitor is to have its own connection terminals, HRC
fuses, contactor, indicator lamp and set of discharger resistors.
I. Regulator is to be housed IP31 sheet steel enclosure, and is to have setting
knob for PF selection between 0.8 and 1.0, manual control position, and
signal lights.
J. Instrument Transformers are to be provided at incoming circuit breaker(s) of
MDB.
2.11 WIRING
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A. Arrangement: wiring is to be modularly and neatly arranged on. master
terminal boards with suitable numbering strips and appropriate cartridge type
fuses where required.
B. Connections are to be made at front of terminal board and with no live metal
'exposed.
C. Metal cases of instruments, control switches, relays etc. are to be connected,
by copper conductors not less than 2.5 mm2 section, to nearest earthing bar.
D. Control Wiring: copper, PVC insulated, 85 deg. C, 600 V grade, and PVC
sheathed. for multi-core cables. Finely .stranded copper conductor, silicon
rubber insulated cables are to be used In proximity to higher temperature
components and as flexible cable.
E. Ferrules: wires are to be fitted with numbered ferrules of approved type at
each termination.
2.12 MISCELLANEOUS
A. Schematic and wiring diagram is to be provided suitably located within each
cubicle.
2.13 WORKS TESTS
A. All assemblies shall be tested in accordance with the requirements of IEC
60439 standards part 1, plus requirements of associated standards.
B. TYPE TESTED ASSEMBLIES (TTA)
TTAs are specified, certification shall be provided for all type and routine
tests to IEC 60439 standards.
C. TYPE TESTED ASSEMBLIES
TTAs are specified, compliance with the test requirements of IEC 60439.
Verification of the Type Testing Certification or the appropriate
extrapolation calculations shall be provided. Certificates shall also be
provided for routine tests.
D. Works tests shall include inspection of all wiring and a complete electrical
functioning test.
E. Protection relays shall be tested by primary current injection with currents
equal to overload, short-circuit and earth fault conditions.
F. Works tests shall be done in the presence of the engineer.
2.14 FIELD TESTING
A. ASSEMBLES
All assemblies shall be subjected to the routine tests as defined in IEC, 60439
standards. after installation on site. Test certificates shall be provided.
B. FUNCTIONAL UNITS
All functional units shall be checked for correct mechanical operation.
C. PROTECTION CIRCUITS
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All protection circuits in with relays used shall be tested for correct operation
by secondary injection of test currents. This shall be carried out at currents
equivalent to overload, short-circuit and earth fault conditions.
D. CURRENT TRANSFORMERS
Protection circuits using current transformer (CT) operated relays shall be
tested by primary injection of current to prove the transformer ratio.
2.15 COMMISSIONING
A. Following the satisfactory conclusion of inspections and tests on completed
sections of the works, each switchgear assembly shall be duly commissioned
and left in full working order. The term "Commissioning" shall be deemed to
include:
(1) The energizing of functional device circuits and equipment which have
previously been inspected, tested found to be satisfactory and capable of
being energized with compete safety.
(2) The starting up of all electrically powered plant and equipment, including
that supplied and installed under other contracts, and as specified in the
schedules.
(3) The verification of the performance of each switchgear assembly relative to
all such plant and equipment by the carrying out where required, of further
tests and the making of all necessary adjustments or as to obtain optimum
performance.
(4) The proving of all interlock operations in all possible combinations and the
operation of all control systems, metering and indications to meet the
performance requirements specified.
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PART 3- EXECUTION
3.01 EXAMINATION:
A. Examine areas and conditions under which switchboards and components are
to be installed, and notify Engineer in writing of conditions detrimental to
proper completion of the work. Do not proceed with the work until
unsatisfactory conditions have been corrected in a manner acceptable to the
Installer.
3.02 INSTALLATION OF SWITCHBOARDS.
A. Install switchboards as indicated, in accordance with manufacturer's written
instructions, and with recognized industry practices; complying with
applicable requirements of applicable standards or codes approved.
B. Equipment Bases: ensure that concrete bases and foundations provided for
installation of equipment are constructed in accordance with approved shop
and construction drawings and equipment manufacturers' drawings and that
holes for fixing bolts and provisions for passage of cables etc. are provided as
required.
C. Built-in items: ensure that equipment supports, fixings and the like, and
sleeves for passage of feeders and cables which are to be built into concrete
foundations, bases, cable trenches or building structure are provided as and
when required and that they are properly installed.
D. Equipment: install on concrete bases etc., and assemble completely plumb
and level, before grouting in holding-down bolts.
E. Supports and Terminations: install all incoming and outgoing cable supports,
cable ends and termination fittings required for power and control cables.
F. Relays: set in accordance with manufacturer's instructions and in accordance
with an approved scheme.
G. Make good damaged painted surfaces, clean and apply rust-inhibiting prime
coat and two finishing coats of approved enamel upon delivery of equipment
to site, or as required by the Engineer.
H. Tighten connectors and terminals, including screws and bolts, in accordance
with equipment manufacturer's published torque tightening values for
equipment connectors. Where manufacturer's torque requirements are not
indicated, tighten connectors and terminals to comply with tightening torques
specified in applicable standards.
I. Coordinate as necessary to interface installation of switchgears with other
works.
J. Fasten enclosures firmly to wall and structural surfaces, ensuring that they are
permanently and mechanically anchored. Provide all angle units and
accessories for proper mounting.
K. Provide properly wired electrical connections for switchgears within
enclosures.
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L. Double lugging is not permitted.
M. Fill out switchgears circuit directory card upon completion of installation
work.
N. Provide equipment earthing connections sufficiently tight to assure a
permanent and effective ground for panelboards.
O. Provide 6.0 mm minimum thick x100 cm wide insulation mat in front of low
voltage switchgear and near of freestanding equipment and extend 50cm
beyond ends.
3.03 FIELD QUALITY CONTROL:
A. Equipment: inspect equipment upon delivery to Site and report any damage
to the Engineer.
B. Switch gear: inspect and check switch gear for completeness, component
ratings, types, sizes, and wiring connections. Check phasing of busbars,
contacts and clearances.
C. Tests: after installation and before handover, carry out all tests required by
the governing codes and any other tests the Engineer may require to check
compliance of installation with the Specification, including insulation
resistance tests and operational tests.
D. Main and Control Circuits: using 1000 V megger (2000 Megohm range),
check insulation resistance between phases, between phases and
earth/enclosure and between neutral and earth.
E. Primary Injection Tests: provide portable test equipment to test time-delay
characteristics of circuit breakers by simulating an overload or fault
condition. Measure and record all test results and ambient conditions and
compare with manufacturer's data.
F. Instantaneous Trip Elements: test by high current primary injection, using
high- current primary injection test- sets and report all readings.
G. Routine tests on site are to be carried out on every main distribution board in
accordance with the Standard specified (IEC 439 or BS 5486: Part 1) for
FBAs assembled from standardized components outside the works of the
manufacturer. Routine tests are also to be carried out on every FBA,
delivered to site, if requested by the Engineer.
H. Prior to energization of circuitry, check all accessible connections to
manufacturer's torque tightening specifications.
I. Prior to energization of switchboards, check with ground resistance tester
phase-to-phase and phase-to-ground insulation resistance levels to ensure
requirements are fulfilled.
J. Prior to energization, check switchboards for electrical continuity of circuits,
and for short-circuits.
K. Equipment shall be tested and full type test certificate issued by an approved
independent test laboratory shall be submitted.
L. Adjust operating mechanisms for free mechanical movement.
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M. After energization check phase balancing and adjust accordingly.
N. Touch-up scratched or marred surfaces to match original finishes.
3.04 ADJUSTING AND CLEANING:
A. Adjust operating mechanisms for free mechanical movement.
B. Touch-up scratched or marred surfaces to match original finishes.
3.05 EARTHING:
A. Provide equipment earthing connections for switchboards as indicated.
Tighten 1 connections to comply with tightening torques specified in
applicable standards to assure permanent and effective earthing.
3.06 DEMONSTRATION:
A. Subsequent to wire and cable hook-ups, energize switchboards and
demonstrate functioning in accordance with requirements. Where necessary,
correct malfunctioning units, and then retest to demonstrate compliance.
3.07 INTER CONNECTION WITH OTHER SYSTEMS
A. The system supplier is responsible to provide all required switches, auxiliary
contacts relays, wiring terminal blocks transducers to provide signaling and
metering information for the building management system (BMS) to accept
START/STOP, open/close, set point from it.
B. Relevant signals are listed under controls, (BMS) and motor control panels
drawings and data schedules.
C. All signals to BMS system should be potential free to actuate devices of less
than 20 VA.@220 volt.
D. If any device will need more than 20 VA. at any operating condition the
supplier should add interposing relays.
E. All analog measures coming or going to the (BMS) should be coordinate
with the (BMS) supplier (either 4-20 MA or 1-5 volt or -10 volt) or directly
connected to the (BMS) communication bus.
END OF SECTION 16425
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